The case of a CUNY professor violently strangled by a gay lover — in what the young killer claimed was a “rough sex” accident — will be retried after a Manhattan jury declared itself hopelessly deadlocked today.

After seven days of deliberations, jurors said they could not agree on whether accused murderer Davawn Robinson, 24, of Paterson, NJ, intended to cause the death of popular Spanish professor Edgard Mercado, 39.

Mercado was found dead on the bedroom floor of his East Village apartment two years ago — the rope to his capoeira martial arts uniform still tight around his neck. Robinson admitted strangling him, but claimed he was only guilty of reckless manslaughter or negligent homicide, not murder.

Prosecutors had countered that the burst capillaries in the victim’s eyes, along with facial bruising and severe neck injuries — including crushed bone and cartilage — proved that Mercado had struggled against a brutal, murderous attack at Robinson’s hands. Robinson had also stole the victim’s laptop and cellphone, and had initially given officials an elaborately false self defense story, prosecutors pointed out.